The present invention relates to an apparatus for and a method of testing-running characteristics of a part of a vehicle as an object to be tested on a test bench.
Related Art
A flat belt type chassis dynamo has been proposed in order to evaluate the maneuvering stability of the vehicle, instead of a conventional drum type chassis dynamo. For example, Japanese Patent Unexamined Publication No. 6-249753 discloses a method wherein support parts are provided, corresponding to wheels of the vehicle, on the upper surfaces of movable parts which can be swung by first hydraulic jacks actuated independent from one another, and which can be swung widthwise of the vehicle by second hydraulic jacks actuated independent from one another, and flat belts making contact with the wheels of the vehicle are provided respectively to the support parts, the movable parts being inclined so as to reproduce a climbing slope and a ramp and the support parts being inclined so as to variously change ground contact conditions of the wheels of the vehicle so as to reproduce various disturbances exhibited by the road surface, thereby precisely testing the maneuverability of the vehicle in various road surface conditions over a wide range.
Dynamic load variation occurs at each of wheels of a vehicle during acceleration or turning during actual running of vehicle, in addition to static load variation caused by a climbing slope or a ramp as mentioned above. For example, during acceleration, loads at rear wheels become larger, while during deceleration, loads at front wheels become larger, and during turning, loads at outer wheels become larger. These occur irrespective of a load configuration such as a flat road or a ramp. During acceleration, an inertia force is exerted to the gravitational center of the vehicle while a drive force is exerted to the ground contact points of the tires, and accordingly, moments are generated around the pitching axis. Load displacement from the front wheels to the rear wheels occurs, corresponding to forces balancing the above-mentioned pitching moments. Similarly, a centrifugal force is exerted to the gravitational center of the vehicle during turning while a cornering force is exerted to a ground contact point, and accordingly, a rolling moment is effected. A displacement of a load from an outer wheel to an inner wheel occurs, corresponding to a force balancing with the rolling moment.
Further, the wheels stroke vertically while they are guided by suspension links. Since the links have a limited length, the alignment with respect to the road surface is always changed as the wheels stroke.
The variation in load and variation in the alignment intricately influence upon each other so as to excessively affect the friction forces between the tires and the road surfaces, and are influence factors which are not negligible for analyzing the maneuverability of the vehicle, in particular abrupt changes in maneuvering.
Further, in the case of testing a vehicle on actual running, variations in the attitude of the vehicle continuously affect constraint conditions with respect to inputs to the four wheels. However, in the case of testing a suspension for a single wheel as a module, influence caused by variation in the attitude of an overall vehicle cannot be taken into account, that is, it has been impossible to evaluate how the suspension for a single wheel affects the maneuvering of an overall vehicle.